A liquid crystal display has been used widely more and more year by year as a space-saving image display device that consumes little electric power. A liquid crystal display has heretofore been greatly disadvantageous in that it has a great dependence of image on viewing angle. In recent years, however, a VA mode of high viewing angle liquid crystal has been put into practical use. With this trend, the demand of liquid crystal displays has been rapidly growing also in the market of electrical appliance requiring a high fidelity image such as television set.
Under these circumstances, the optically-compensatory member to be used in the improvement of tint, contrast and their viewing angle dependence in liquid crystal displays, too, is required to have further improvement in optical compensation properties.
Referring to optically-compensatory film for VA mode liquid crystal displays, it has heretofore been known that one comprising an A plate and a C plate in combination has a great effect of improving the contrast viewing angle.
Further, WO2004/068226 A1 discloses a technique which involves optical compensation by a polymer film having wavelength dispersion which is different from in-plane retardation to thickness-direction retardation, whereby contrast can be further enhanced and tint in black display can be close to gray.
However, this method leaves something to be desired in effect of improving tint viewing angle. This method is disadvantageous in that the tint change becomes remarkable particularly after prolonged display under high temperature and humidity conditions. Thus, it has been desired to provide improvements in this method.
Further, JP-A-2004-326089 discloses a technique involving a stacking of retardation layers comprising a retardation layer having a positive refractive anisotropy and an optical axis in the in-plane thereof and a retardation layer having a negative refractive anisotropy and an optical axis in the direction normal to the surface thereof stacked in combination, wherein as the retardation layer having a positive refractive anisotropy and an optical axis in the in-plane thereof there is used a stretched polymer film having reverse wavelength dispersion characteristics such that retardation falls as the wavelength drops and as the retardation layer having a negative refractive anisotropy and an optical axis in the direction normal to the surface thereof there is used a coat layer having true wavelength dispersion characteristics such that retardation rises as the wavelength drops, whereby the contrast can be further enhanced and the tint in black display is close to gray.
However, the above cited technique is disadvantageous in that the use of the aforementioned laminate of retardation layers as protective film for polarizing plate causes the deterioration of the polarization properties of the polarizer and the polarizing plate. This citation is also disadvantageous in that when the adhesion of the polarizer is insufficient, the protective film is peeled off the polarizer during the preparation of the polarizing plate or the storage of the polarizing plate thus prepared under high temperature and humidity conditions. Accordingly, the aforementioned laminate of retardation layers must be used stuck to other polarizing plate protective films other than cellulose acetate film with an adhesive before use. Improvements have been desired in respect to productivity and cost.